Polychloro parathio phenols

ABSTRACT

Chlorinated (alkylthio)phenols, chlorinated (alkenylthio)phenols, and chlorinated (cycloalkythio)phenols are described which are useful as miticides. These phenols often possess herbicidal, insecticidal, and/or fungicidal properties. Examples of these compounds are 2,3,5,6-tetrachloro-4(methylthio)-phenol and 2,3,6-trichloro-4-(methylthio)phenol.

United States Patent [1 1 Bissinger et a1.

[451 Nov. 26 1974 POLYCHLORO PARATHIO PHENOLS [75] inventors: William E.Bissinger, Akron; Donald E. Hardies, Wadsworth; Jerome M. Lavanish,Akron, all of Ohio [73] Assignee: PPG Industries, Inc., Pittsburgh, Pa.

[22] Filed: Sept. 11, 1972 [21] Appl. No.: 288,220

Related U.S. Application Data [62] Division of Ser. No. 76,651, Sept.28, 1970, Pat. No.

[52] U.S. Cl. 71/98 [51] Int. Cl A0ln 9/12 [58] Field of Search 71/98[56] References Cited UNITED STATES PATENTS 3,282,979 11/1966Reifschneider et a1. 71/98 X Primary ExaminerLewis Gotts AssistantExaminer-Catherine L. Mills Attorney, Agent, or Firm-George G. Morris[57] ABSTRACT 18 Claims, N0 Drawings .1 POLYCHLORO PARATH IO PHENOLSThis is a division of application Ser. No. 76,651, filed Sept. 28, 1970,now US. Pat. No. 3,723,538.

In accordance with this invention, there are provided phenols which areeffective as miticides and which also often possess herbicidal,insecticidal, and/or fungicidal properties.

Phenols here contemplated may be represented by I the formula:

wherein nis3or4;and R is lower alkyl, lower alkenyl, or lowercycloalkyl.

Subclasses within the scope of the above formula aretrichloro-4-(alkylthio)phenol, tetrachloro-4-(alkylthiol-phenol,trichloro-4-(alkenylthio)phenol, tetrachloro-4-(alkenylthio)phenol,trichloro-4-(cycloalkylthio)phenol, andtetrachloro-4-(cycloalkylthio)phenol. The trichloro-4-(alkylthio)phenolsand the tetrachloro- 4-(alkylthio)phenols are preferred. 7

When R in the above formula is lower alkyl, it usually contains from Ito 8 carbon atoms.'lt may be either straight or branched. Most often Ris methyl or ethyl. Methyl is preferred.

When R is lower alkenyl, it generally contains from 3 to 8 carbon atoms.Ally] is most often used.

When R is lower cycloalkyl, it typically contains from 3 to 8 carbonatoms. Most often it contains 5 to 8 carbon atoms. Cyclohexyl ispreferred.

When the value of n is 3 in the above formula, the chlorine atoms may bearranged in either the 2,3,6-positions or the 2,3,5-positions. Theformer arrangement is preferred.

An important class falling within the generic invention is representedby the formula:

wherein the value of n is 3 or 4. The members of this class are2,3,5-trichloro-4-(methylthio)phenol,2,3,6-trichloro-4-(methylthio)phenol, and2,3,5,6-tetrachloro-4-(methylthio)phenol.

Compounds which exemplify the phenols of the invention are:

2,3,5-trichloro-4-(methylthio)phenol 2,3,5-trichloro 4-(ethylthio)phenol2,3,5-trichloro-4-(propylthio)phenol2,3,5-trichloro-4-(isopropylthio)phenol2,3,5-trichloro-4-(butylthio)phenol2,3,5-trichloro-4-(sec-butylthio)phenol2,3,5-trichloro-4-(isobutylthio)phenol I2,3,5-trichloro-4-(2,2,3,3-tetramethylbutylthio)- phenol 2,3,5-trichloro-4-(allylthio )phenol 2,3 ,5-trichloro-4-( 3-pentenylthio)phenol 2,3 ,5-trichloro-4-( cyclopropylthio )phenol 2,3,5-trichloro-4-( cyclopentylthio )phenol 2,3,5-trichloro-4-(cyclohexylthio )phenol2,3,5-trichloro-4-(cycloheptylthio)phenol 2,3 ,5-trichloro-4-(cyclooctylthio )phenol 2, 3 ,6-trichloro-4-(methylthio )phenol 2,36-trichloro-4-( ethylthio )phenol 2 ,3 ,6-trichloro-4-(propylthio)phenol 2 ,3 ,6-trichloro-4-( isopropylthio )phenol 2,3 ,6-trichloro-4-(butylthio )phenol 2,3 ,6-trichloro-4-( sec-butylthio )phenol 2 ,3,6-trichloro-4-( isobutylthio )phenol 2 ,3 ,6-trichloro-4-(tert-butylthio )phenol 2,3,6-trichloro-4-(pentylthio)phenol2,3,6-trichloro-4-( l ,Z-dimethylpropylthio )phenol 2,3,6trichloro-4-(hexylthio)phenol2,3,6-trichloro-4-(4-methylpentylthio)phenol 2,3,6-trichloro-4-( l,3-dimethylbutylthio)phenol 2,3,6-trichloro-4-(2-ethylbutylthio)phenol2,3,6-trichloro-4-(heptylthio)phenol2,3,6-trichloro-4-(S-methylhexylthio)phenol2,3,6-trichloro-4-(2,2-dimethylpentylthio)phenol 2,3,6-trichloro-4-( l,2,2-trimethylbutylthio)phenol 2,3,6-trichloro-4-( l,2,3-trimethylbutylthio)phenol 2,3,6-trichloro-4-(l-ethyl-2,2-dimethylpropylthio)- phenol 2,3,6-trichloro-4-( l,Z-diethylpropylthio)phenol 2,3,6-trichloro-4-(octylthio)phenol2,3,6-trichloro-4-(Z-methylheptylthio)phenol. 2,3,6-trichloro-4-( l,4-dimethylhexylthio)phenol2,3,6-trichloro-4-(2,2,3-trimethylpentylthio)phenol2,3,6-trichloro-4-(2-ethyl-2-methylpentylthio)- phenol2,3,6-trichloro-4-( l,2,2,3-tetramethylbutylthio)- phenol 2,3,6-trichloro-4-( 2,2-diethylbutylthio )phenol 2,3,6-trichloro-4-(l-isopropyl-2-methylbutylthio phenol 2,3 ,6-trichloro-4-( allylthio)phenol 2,3,6-trichloro-4-(2-pentenylthio)phenol2,3,6-trichloro-4-(3-hexenylthio)phenol2,3,6-trichloro-4-(cyclopropylthio)phenol2,3,6-trichloro-4-(cyclobutylthio)phenol2,3,6-trichloro-4-(cyclopentylthio)phenol 2,3,6-trichloro-4-(cyclohexylthio )phenol 2 ,3 ,6-trichloro-4-( cycloheptylthio )phenol 2,3,6-trichloro-4-( cyclooctylthio)phenol2,3,5,6-tetrachloro-4-(methylthio)phenol 2,3 ,5 ,6-tetrachloro-4-(ethylthio )phenol 2,3 ,5 ,6-tetrachloro-4-(propylthio)phenol2,3,5,6-tetrachloro-4-(isopropylthio)phenol 2,3 ,5 ,6-tetrachloro-4-(butylthio )phenol 2,3,5,6-tetrachloro-4-(sec-butylthio)phenol 2,3,5,6-tetrachloro-4-( isobutylthio)phenol 2,3,5 ,6-tetrachloro-4-(tert-butylthio)phenol 2,3 ,5 ,6-tetrachloro-4-(pentylthio )phenol 2 ,3,5 ,6-tetrachloro-4-( 2-methylbutylthio )phenol 2,3,5 ,6-tetrachloro-4-(2,2-dimethylpropylthio)- phenol 2,3,5 ,6-tetrachloro-4-(hexylthio)phenol 2 ,3 ,5 ,6-tetrachloro-4-( 3-methylpentylthio )phenol2,3,5,6-tetrachloro-4-( l ,Z-dimethylbutylthio)phenol 2,3,5,6-tetrachloro-4-( 2,3-dimethylbutylthio )phenol 2,3 ,5,6-tetrachloro-4-( 2,3-dimethylhexylthio)phenol 2,3,5 ,6-tetrachloro-4-(2,4-dimethylhexylthio)phenol 2,3,5,6-tetrachloro-4-(l,2,4-trimethylpentylthio)- phenol 2,3,5 ,6-tetrachloro-4-(2,2,4-trimethylpentylthio)- phenol 2,3,5,6-tetrachloro-4-(2,4,4-trimethylpentylthio phenol 2,3 ,5 ,6-tetrachloro-4-(2,3,4-trimethylpentylthio)- phenol 2,3,5 ,6-tetrachloro-4-(3-ethyl-3-methylpentylthio)- phenol 2,3,5 ,6-tetrachloro-4-(2,2,3,B-tetramethylbutylthio)- phenol 2,3,5 ,6-tetrachloro-4-(l,2,2,3-tetramethylbutylthio phenol 2,3,5 ,6-tetrachloro-4-(l-ethyl-2,Z-dimethylbutylthio )-phenol 2,3,5,6-tetrachloro-4-(l,Z-diethylbutylthio)phenol 2,3,5,6-tetrachloro-4-(2,2-diethylbutylthio)phenol 2,3,5,6-tetrachloro-4-(l-propyl-2-methylbutylthio)- phenol 2,3,5,6-tetrachloro-4- I-isopropyl-2-methylbutylthio)-phenol. 2,3,5,6-tetrachloro-4-(l-isopropyl-2-methylpropylthio)-phenol2,3,5,6-tetrachloro-4-(allylthio)phenol2,3,5,6-tetrachloro-4-(2-pentenylthio)phenol 2,3,5 ,6-tetrachloro-4-(3-pentenylthio )phenol 2,3,5,6-tetrachloro-4-(3-hexenylthio)phenol2,3,5,6-tetrachloro-4-(4-hexenylthio)phenol2,3,5,6-tetrachloro-4-(cyclopropylthio)phenol2,3,5,6-tetrachloro-4-(cyclobutylthio)phenol2,3,5,6-tetrachloro-4-(cyclopentylthio)phenol2,3,5,6-tetrachloro-4-(cyclohexylthio)phenol 2,3 ,5,6-tetrachloro-4-(cycloheptylthio )phenol2,3,5,6-tetrachl0ro-4-(cyclooctylthio)phenol These phenols may beprepared by the reaction, in the presence of a base, of theappropriately chlorine substituted thiocyanatophenol and an alcohol ofthe formula ROI-l wherein R is lower alkyl, lower alkenyl, or lowercycloalkyl.

Another method of preparation may be achieved by the reaction, in thepresence of a base, of the appropriately chlorine substitutedthiocyanatophenol and an organic halide of the formula RX wherein R islower alkyl, lower alkenyl, or lower cycloalkyl and X is ahalogen,usually chlorine, bromine, or iodine.

The chlorine substituted thiocyanatophenol starting material may beprepared by reacting l) the appropriately chlorine substituted phenolhaving an unsubstituted para-site with (2) ammonium thiocyanate or analkali metal thiocyanate and (3) an oxidizing agent such as chlorine orbromine.

Reactions similar to the above are shown in U.S. Pat. Nos. 3,231,623;3,246,039; 3,274,257; 3,282,979; 3,303,206; and 3,303,209.

The phenols of this invention may be prepared by the hydrolysis of acompound represented by the structural formula wherein n is 3 or 4 and Ris as hereinbefore defined, in the presence of a solvent and at leastone base selected from the group consisting of alkali metal hydroxideand alkaline earth metal hydroxide. Sodium hydroxide or potassiumhydroxide is most often used. Potassium hydroxide is preferred.Exemplary solvents include the alcohols having from 1 to 10 carbonatoms. The preferred solvents are the tertiary alcohols having from 4 to10 carbon atoms. Examples of these solvents are methyl alcohol, ethylalcohol, isopropyl alcohol, tertbutyl alcohol, l-methylamyl alcohol,tert-amyl alcohol, normal hexyl alcohol isohexyl alcohol, 2-ethylhexylalcohol, l, l -diethylpropyl alcohol, normal decyl alcohol,l,l-diethyl-3-methylamyl alcohol. Tertiary amyl alcohol or tertiarybutyl alcohol is preferred. Mixtures of solvents and/or bases are withincontemplation. In a preferred embodiment R is methyl. Hydrolysis istypically carried out at a temperature ranging from about 30C. to about200C. although other temperatures can be used. Most often thetemperature is in the range of 80C. to 150C. The reaction is ordinarilycarried out at atmospheric pressure although greater or lesser pressuresmay be used if desired. The reaction progresses satisfactorily when thereaction mixture is heated to reflux, usually at atmospheric pressure.

Preparation of the contemplated phenols is illustrated by Examples I IV.

EXAMPLE 1 A 300 ml. two-necked flask is equipped with a magneticstirrer, thermometer, and dropping funnel. The flask is immersed in awet ice bath and charged with 100 m1. of methyl alcohol, 6.0 g. of2,3,5,6- tetrachlorophenol, and 22 g. of potassium thiocyanate. To thissolution at C. C. a solution of 4.3 ml. of bromine in 25 ml. of methylalcohol (saturated with sodium bromide) is added dropwise over a periodof 1.5 hours. During the addition a precipitate forms and the mixturebecomes quite thick. After an additional two On taking a melting pointof this product, it starts to melt at 165C., then darkens andresolidifies above 185C. The product is analyzed for carbon, hydrogen,

nitrogen, and chlorine. The results expressed in percent by weight areshown in Table l.

Table 1 Analysis of 2,3,5,fi-tetrachlow-44hiocyanatophenol C H N ClCalculated for C,HCl NOS 29.1 0.35 4.85 49.2

Found 28.96 0.42 4.86 48.62

A 50 ml. flask is charged with 4.2 g. of2,3,5,6-tetrach1oro-4-thiocyanatophenol, 2,2 g. of methyl iodide, and 20ml. of methanol. A solution of 3.0 g. of 85 percent potassium hydroxidein 10 ml. of water is added dropwise with stirring over a period of 70minutes. After stirring at room temperature for 2 hours, the mixture isstripped to dryness on a rotary film evaporator. The residue isdissolved in 20 ml. of

. water. This solution is poured into a mixture of 10 ml.

of concentrated hydrochloric acid and 25 g. of ice. The whiteprecipitate which forms is separated from the bulk of the liquid byfiltration and dried. The residue weighs 3.8 grams. Recrystallizationfrom a mixture of normal hexane and benzene gives 2.4 g. of pale yellowcrystals having a melting point range of 121C. to 123.5C. The product is2,3,5,6-tetrachloro-4-(methylthio)pheno1 and may be depicted as havingthe structural formula:

- l Cl SCI-l EXAMPLE 11' A 500 ml. three-necked flask is equipped with amechanical stirrer, a thermometer, and a dropping funnel. The flask isimmersed in a wet ice bath and charged with 200 ml. methyl alcohol, 20.0g. of 2,3,6- trichlorophenol, and 35.0 g. of potassium thiocyanate. Tothe stirred mixture at 4C. 8C. a solution of 1 1.0 ml. of bromine in 40ml. of methyl alcohol (saturated with sodium bromide) is added dropwiseover a period of one hour. The mixture is stirred an additional halfhour and then poured into 1000 ml. of water. The aqueous mixture isextracted once with 150 ml. of diethyl ether and three times with 100ml. portions of diethyl ether. The combined ether extract is dried oversodium sulfite, filtered, and stripped on a rotary evaporator therebyyielding 28 g. of yellow solid. Gas chromatopgraphic analysis ofmethylene chloride solu- .tions of the yellow solid show the yellowsolid to be about 60 percent 2,3,6-trichloro-4-thiocyanatophenol and therest 2,3,6-trichlorophenol. The yellow solid is redissolved in 30 ml. ofmethyl alcohol along with 40 g. of potassium thiocyanate. To the stirredmixture at 3C 8C. a solution of 1 1.0 ml. of bromine in 40 ml. of methylalcohol (saturated with sodium bromide) is added dropwise over a periodof 40 minutes. After stirring an additional hour, the reaction mixtureis extracted once with 150 ml. of diethyl ether and three times with 100ml. portions of diethyl ether. The combined ether extract is dried oversodium sulfite, filtered, and stripped on a rotary evaporator therebyyielding 21.0 g. of yellow solid. Gas chromatographic analysis of thisyellow solid shows it to be more than percent2,3,6-trichloro-4-thiocyanatophenol. This yellow solid is dissolved inhot benzene, filtered while hotto remove a dark red semi-solid, andcooled to give 14.4 g. of light yellow2,3,6-trichloro-4-thiocyanatophenol, melting point range 128C. 129C.,

A ml. flask is charged with 4.1 g. of 2,3,6-trichloro-4-thiocyanatophenol, 2,3 g. of methyl iodide, and 30 ml. ofmethanol. A magnetic stirring bar is added and the flask is fitted witha pressure equalized addition funnel charged with 2.7 g. of potassiumhydroxide in 15 ml. of water. The potassium hydroxide solution is addeddropwise over a period of 30 minutes with stirring. After 2 hours themixture is concentrated under vacuum until about 25 ml. of solutinremained.

This is poured into a mixture of 20 ml. of concentrated hydrochloricacid and 25 g. of ice. The tan solid which separates is filtered, washedwith two 25 ml. portions of water, and dried to give 3.8 g. of tanpowder. Recrystallization from a mixture of normal hexane and chloroformgives, after filtration and drying, 1.5 g. of tan nee- 5 dles having amelting point range of 128C. 129C.,

(broad, OH) and nuclear magnetic resonance signals at 2.498 (singlet,31-1) and 7.225 (singlet, ll-l). The spectra are consistent with2,3,6-trichloro-4-(methylthio)phenol. The product is analyzed forcarbon, hydrogen, and chlorine. The results expressed in percent byweight are shown in Table 2.

' Table 2 Analysis of.2,3,6-trichloro-4-(methylthio)phenol C H ClCalculated for C-,H Cl,OS 34.5 2.0 43.7

Found 338 2.0 44.5

The product may be depicted as having the structural formula:

SCH

EXAMPLE 111 The compound 2,3,5-trichloro-4-thiocyanatophenol is preparedin a manner similar to that of Example 11 using 2,3,5-trichlorophenol inlieu of 2,3,6- trichlorophenol. The compound2,3,5-trichloro-4-(methylthio)phenol is prepared in a manner similar tothat of Example 11 using 4.1 g. of 2,3,5-trichloro-4- thiocyanatophenolin place of 4.1 g. of 2,3,6-trichloro- 4-thiocyanatophenol.

The product may be depicted as having the structural formula:

Example 1V illustrates another way in which 2,3,5,6-tetrachloro-4-(methy1thio)phenol may be prepared.

EXAMPLE IV addition of 50 ml. of water gives a cloudy solution which iswashed with two 25 ml. portions of benzene. The aqueous solution isheated on a steam bath until enough residual benzene is driven off forthe solution to become clear. The solution is allowed to cool.Concentrated hydrochloric acid is then added until no further cloudinessappeared. An oil separates which is dissolved in benzene. The benzenesolution is dried and concentrated on a rotary film evaporator to give4.7 g. of waxy brown crystals. They are dissolved in a refluxing mixtureof normal hexane and benzene, filtered while still hot, and allowed tocool. The crystals which form are filtered and dried. They weigh 1.8 g.and have a melting point range of 108C. 116C. A second recrystallizationfrom a mixture of normal hexane and chloroform gives 1.1 g. of tancrystals with a melting point range of 119C. l20.5C.,

.. Eli-.2 29. 22 32-.

Table 3 Analysis of 2,3,5,6-Tetrachloro4(methylthio)phenol C H ClCalculated for 30.3 1.5 51.2

C-,H Cl,OS

Found 29.3 1.5 51.9

The product may be depicted as having the structural formula:

SCH

In general, the phenols of this invention may be used to kill or retarddevelopment of mites.

In one embodiment the phenol is applied directly. to the mites. Inanother embodiment the phenol is applied to regions where mites arelikely to be found in order to kill the mites present or to precludemite populations from becoming established.

Usually formulations containing from about 5 to about 2,000 parts permillion by weight (ppm) of the phenol compound are applied. Typicalformulations contain from about 10 to about 1,000 ppm. Oftenformulations containing from about 10 to about ppm are used.

The type of formulation used may vary. Solutions and suspensions of thephenol are effective. The usual method of applying solutions orsuspensions is to drench the area of application. Sprays', showers,mists, and dips may be used for this purpose. When some of the moreactive phenols are used, particularly at the higher concentrations, acomplete drenching is not necessary. Mists are often used where a drenchis not desired. 1

The phenol formulations of the invention may also be applied in the formof a powder or dust. These powders or dusts may contain diluents suchas, for example, aluminum silicate, bentonite, calcium carbonate,calcium silicate, diatomaceous silica, hydrated lime, pulverizedlimestone, montmorillonite, pulverized phosphate rock, silica, talc, orvermiculite.

The concentration of the phenol compound in the formulation and thetotal amount applied will vary depending upon the particular phenolbeing employed and the particular mite being confronted. Other factssuch as season of the year, environmental conditions,

and stage of mite development all have their effect.

The following specific embodiments illustrate, by way of example, thebasic principles of the present invention.

EXAM PLE V Potted horticultural bean plants (Phaseolus vulgaris L.) atgrowth stage when primary leaves are approximately 1 inch long areinfested with two-spotted spider mites (Tetrany'chus urticae) 24 hoursprior to treatment, insuring establishment of adults and deposition ofeggs at the time of treatment.

A stock acetone emulsion is prepared having the following composition byweight: 99.75 percent acetone, 0.20 percent sorbitan trioleate (Span85), and 0.05 percent sorbitan monooleate polyoxyalkylene derivative(Tween 80). Test compound is dissolved in a por tion of the stockacetone emulsion. Deionized water is added to yield a concentrated testsolution containing about 10 percent acetone, 0.020 percent Span 85, and0.0050 percent Tween 80. The amount of test compound dissolved in thestock acetone emulsion is such that when diluted with deionized waterthe concentrated test solution has the highest concentration (usually1,000 ppm) of test compound used in the tests. Solutions which areprepared by diluting the concentrated test solution with a mixture ofdeionized water and stock acetone emulsion, which mixture contains about10 percent acetone, 0.020 percent Span 85, and 0.0050 percent Tween 80.Thus, all test solutions always contain about 10 percent acetone, 0.020percent Span 85, and 0.0050 percent Tween 80, irrespective of theconcentration of test compound.

Infested host plants are dipped into agitated solutions of the testcompound, allowed to air dry, provided with a subterranean water source,and held for observation.

Three test plants are used for each unit of treatment.

Table 4 Miticidal Effectiveness of 2,3,5,6-Tetrachloro-4-(methylthio)phenol Against Two-Spotted Spider Mite (Tetranychus urlicae)The procedure of Example V is repeated using 2,3,6-trichloro-4-(methylthio)phenol as the test compound. The results areshown in Table 5.

Table 5 Miticidal Effectiveness of 2,3,6-Trichloro-4- (methylthio)pheno1Against Two-Spotted Spider Mite (-Telranychus urlicae) ConcentrationPercent Mortalitv ppm Initial Ovicidal Residual 1,000 100 0 I00 500 g100 0 100 250 I00 0 96 0 Trace Many of the phenols of the presentinvention possess properties which make them useful as phytocides, asfor example, herbicides. Weeds may be killed by applying to the soil inthe vicinity of the weeds a phytocidal amount of the phenol. Weeds mayalso be killed by bringing the weeds and a phytocidal amount of thephenolinto mutual contact, as for example, by applying the phenol to theweeds. In another embodiment the pheno] is applied to the soil whereweeds are likely to be found in order to preclude weeds from becomingestablished.

The formulations used as phytocides are similar in all material respectsto those described above for miticidal purposes. The concentration ofthe phenol in the formulation and the total amount applied will varydepending upon the particular phenol being employed and the particularweed being confronted. Other factors such as season of the year,environmental conditions, and stage of weed development all have theireffect. Exemplary application rates are from about 0.1 to about 100pounds per acre. Usually the rate will range from about 0.1 to about 20pounds per acre. Rates of from about 0.5 to about 10 pounds per acre aremost often used.

In Examples VII through XIII the following procedure was used: Forpre-emergence testing, appropriate weed species are seeded in individualdisposable 3-inch square containers containing about 2 inches of soil.

After spraying directly on the seeded soil surface, a small amount ofsand, usually about 1/8 to H4 inch in depth, is applied to coverthe'seeds.

For post-emergence testing, appropriate weed species are seeded bygrowth-time requirement schedules in individualdisposable 3 inch squarecontainers cona solvent mixture of 90 percent acetone, 8 percent 10methanol, and 2 percent dimethylformamide by vol;

usually did not recover; l0 all plants killed. Deviations from the aboveprocedure, if any, are reported with the data.

EXAMPLE Vll Test Compound: 2,3,5,6-Tetrachloro-4-(methylthio)phenolPre-Emergence Observations made If) days after applicationPost-Emergence Observations made 13 days after application Pre- PostTest Plant Emergence Emergence 5 lb./A 5 lb./A

Yellow Nutsedge (Cyperus esrulentus L.) 5 8 Wild Oats (Avena falua L.) 29 Jimsonweed (Datum srramonium L.) 0 l0 Velvetleaf (Abulilan IheophrasliMedic.) 2 l() .lohnsongrass (Sorghum halepense Pers.) 4 8 Lambsquarter(Chenopodium album L.) l0 Mustard (Brassim kaher L. C. Wheeler Var.pinnalifldu L. C. Wheeler) 8 10 Yellow Foxtail (Serlariu gluuca Beauv.)2 9 Barnyardgrass (ECIliIlOLIl/lltl crusgulli Beauv.) 2 7 Crabgrass(Digimriu sanguinulis Scop.) 8 8 Buckwheat (Polygmlum ((HH'UIVMIIIS L.)2 IO Morning Glory (mixture of lpumoeu purpurea Roth and lpomoeuIiederacea .lacq.) 5 9 Red Kidney Bean (Phaseulus vulgaris L.)

Primary Leaf Stage l0 Trifoliate Leaf Stage l0 Untreated Controls NormalNormal ume. Insoluble compounds are formulated as wettable powders anddiluted with water and wetting agent before application.

Each carrying tray of pre-emergence and/or post emergence containers,placed on a conveyor belt having a linear speed of 1.5 miles per hour,trips a microswitch which, in turn, activates a solenoid valve andreleases the compound under test. The compound under test is dischargedas sprays at a rate of 50 gallons per acre. Containers used forpre-emergence testing are then watered. Containers for bothpre-emergence and post-emergence testing are then removed to thegreenhouse and held for observation.

Pre-emergence and post-emergence treatments are observed daily forinterim response, final observations usually being made 14 days aftertreatment. Any treatments inducing significant response are held beyondthe 14-day observation period until such responses can be confirmed.Each result is reported as an Injury Rating which is represented asfollows: 0 no visible effect; l, 2, 3 slight injury, plant usuallyrecovered with little or no reduction in top growth; 4, 5, or 6 moderateinjury, plants usually recovered but with reduced top growth; 7, 8, or 9severe injury, plants EXAMPLE Vlll Test Compound:2,3,5,6-Tetrachloro-4-(methylthio)phenol Observations made 21 days afterapplication o)phenol Observations made 14 days after application TestPlant Post-Emergence 1 5 lb/A 2 lh/A l lh/A Yellow Nutsedge (Cyperurerculenms L.) 7 2 0 Wild Oats (Arena falua L.) 10 7 3 .limsonweed(Dalura slramonium L.) l0 l0 l0 Velvetleaf (Ahulilon lheaphrarli Medic.)l0 l0v l0 Johnsongrass (Sorghum Iialepense Pers.) 3 2 l Mustard(Brarsica kaber L. C. Wheeler Var. pinnaufida L. C. Wheeler) l0 l0 9Yellow Foxtail (Selaria glauca Beauv.) l0 7 6 Barnyardgrass(Evlrinuclrlua crusgalli Beauv.) 8 7 6 Crabgrass .(Digilnria sanguinalisScop.) l0 9 7 Buckwheat '(Palygonum convolvulus L.) l0 l0 8 MorningGlory (mixture of lpomoea purpurea Roth and lpomoea hederacea .lacq.) l0l0 9 Red Kidney Bean (Phaseolus vulgaris L.)

Primary Leaf Stage 2 2 2 Trifoliate Leaf Stage 9 5 2 Untreated ControlsNormal Normal Normal EXAMPLE X Test Compound:2,3,6-Trichloro-4-(methylthio)- phenol Pre-Emergence Observations made16 days after application Post-Emergence Observations made 13 days afterapplication Pre Post- Test Plant Emergence Emerence 5 lb./A 5 lb./A

Yellow Nutsedge (Cyperus esculenlus L.) 8 Wild Oats (Avena falua L.) 0 8.limsonweed (Dalura slramonium L.) l0 .Iohnsongrass (Sorghum halepensePers.) 4 l Lambsquarter (Chenopodium album L.) 0 Mustard (Brassica kaberL. C. Wheeler Var. pinnaliflda L. C. Wheeler) 6 l0 Velvetleaf (AbulilonIlleophrasli Medic.) 2 l0 Yellow Foxtail (Selaria glauca Beauv.) 2 I 2Barnyardgrass (Echinochlua crusgalli Beauv.) 2 5' Crabgrass Digitariasanguinalis Scop.) 7 8 Buckwheat (Polygonunl convolvulus L.) 0 10Morning Glory (mixture of lpumoea purpurea Roth and lponwea hederazea.Iacq.) 8 Red Kidney Bean (Plraseulus vulgaris L.)

Primary Leaf Stage 10 Trifoliate Leaf Stage l0 Untreated Controls NormalNormal EXAMPLE XI Test Compound: 2,3,6-Trichloro-4-(methylthio)- phenolObservations made 21 days after application EXAMPLE XII Test Compound:2,3 ,5 ,6-Tetrachloro-4-(methylthio )phenol Observations made 14 daysafter application Post-Emergence Test Plant 2 lb/A 0.5 lb/A Sugar Beet(Bela vulgaris L.) )0 8 Corn (Zea mays L.) 2 l Oats (Arena saliva L.) 23 Red Clover (Trij'alium pralellse L.) 10 9 Soybean (Glycine max [L.]Merr.) 5 5 Cotton (Gorrypium llirsulum L.) 5 l Wheat (Trilicum avslirumL.) 5 2 Peanut (Arachis hypogaea L.) 2 l Rice (Oryza raliva L.) 6 3Kentucky Bluegrass (Pun prau'nsis L.) l l Alfalfa (Medit'agu .ruliva L.)l() 9 Flax (Linum ulrilalisximum L.) 4 2 Pigweed (Amara/Imusre'truflexus L.) 5 2 Wild Oats (Arena falua L.) l() Ouackgrass(Agropymll repens [L.] Beauv.)

C ontinued w Test p 2 lb/A 0.5 lb/A Russian Thistle (Salsa/a kali L.Var. Tenuifnlia Tausch) (from seed) )0 l0 Plorsenettle (Sulanunlcarolinense L.) (from seed) 7 5 Purple Nutsedge ((yperus mlumlus L.)

' (from tubers) U 0 Peppergrass (Lepidum mmpeslre [L] R. Br.) 8 5Chickweed (Slellaria media [L.] Cyrillo) 9 7 Cocklebur (Xanllliumpvnnrylrallicum Wallr.) l0 4 Giant Foxtail (Seraria faberii Herrm.) l 0.lohnsongrass (Sorghum halepenre [L.] Pers.)

(from rhizomes) O 0 Hedge Bindweed (Convulvulur Sepium L.)

(from rhizomes) 7 4 Quackgrass (Agropyron repens [L.] Beauv.)

(from rhizomes) 0 0 Post-Emergence Test Plant 2 lb/A 0.5 lb/A Sugar Beet(Bela vulgaris L.)

Corn (Zea mays L.)

Oats (Avena saliva L.)

Red Clover (Trlfalium pralense L.)

Soybean (Glycine max [L.] Merr.)

Cotton (Gassypium hirsulum L.)

Wheat (Trl'licum aeslivum L.)

Peanut (Arazhis Ilypagaea L.)

Rice (Oryza saliva L.)

Kentucky Bluegrass (Poa pralenris L.)

Alfalfa (Medicagv saliva L.)

Flax (Linum ulsilatissl'mum L.)

Pigweed (Amaranlhus relraflexus L.)

Wild Oats (Arena falua L.)

Russian Thistle (Salrala kali L. Var. Tenuifolia Tausch) (from seed)Horsenettle (Solarium caralinense L.) (from seed) 7 Purple Nutsedge(Cyperus rqlundus L.)

(from tubers) Peppergrass (Lapl'dum pampexlre [L.) R. Br.)

Chickweed (Slellaria media [L.] Cyrillo) Cocklehur (Xanlllillmpennrylvanicum Wallr) Giant Foxtail (Selaria faberii Herrm.)

.lohnsongrass (Sorghum llalepenre [L.] Pers.)

(from rhizomes) Hedge Bindweed (Convolvulus Sapium L.)

(from rhizomes) (from rhizomes) O While the invention has been describedwith reference to certain illustrative embodiments, it is not intendedthat it shall be limited thereby except insofar as appears in theaccompanying claims.

We claim:

1. A method of killing weeds which comprises applying to the soil in thevicinity of the weeds a phytocidal amount of a compound represented bythe formula:

wherein n is 3 or 4; and R is lower alkyl, lower alkenyl, or lowercycloalkyl. 2. The method of claim 1 wherein R is selected from thegroup consisting of lower alkyl containing from 1 represented by thestructural formula:

to 8 carbon atoms, lower alkenyl containing from 3 to 8 carbon atoms,and lower cycloalkyl containing from 3 to 8 carbon atoms.

3. The method of claim 1 wherein R is lower alkyl containing from 1 to 8carbon atoms.

4. The method of claim 1 wherein the compound is represented by thestructural formula:

sen

wherein n is 3 or 4.

5. The method of claim 4 wherein the compound is2,3,6-trichloro-4-(methylthio)phenol.

'6. The method of claim 4 wherein the compound is2,3,5,6-tetrachloro-4-(methylthio)phenol.

7. A method of killing weeds which comprises bringing into mutualcontact the weeds and a phytocidal amount of a compound represented bythe structural formula:

wherein n is 3 or 4.

11. The method of claim 10 wherein the compound is2,3,6-trichloro-4-(methylthio)phenol.

12. The method of claim 10 wherein the compound is2,3,5,6-tetrachloro-4-(methylthio)phenol.

13. A method of precluding the establishment of a weed population in thesoil comprising applying to the soil an effective amount of a compoundrepresented by the structural formula:

wherein n is 3 or 4; and R is lower alkyl, lower alkenyl, or lowercycloalkyl.

14. The method of claim 13 wherein R is selected from the groupconsisting of lower alkyl containing from 1 to 8 carbon atoms, loweralkenyl containing from 3 to 8 carbon atoms, and lower cycloalkylcontaining from 3 to 8 carbon atoms.

15. The method of claim 13 wherein R is lower alkyl containing from 1 to8 carbon atoms.

16. The method of claim 13 wherein the compound is represented by thestructural formula:

SCH3

wherein n is 3 or 4.

17. The method of claim 16 wherein the compound is2,3,6-trichloro-4-(methylthio)phenol.

18. The method of claim 16 wherein the compound is2,3,5,6-tetrachloro-4-(methylthio)phenol. V

1. A METHOD OF KILLING WEEDS WHICH COMPRISES APPLYING TO THE SOIL IN THEVICINITY OF THE WEEDS A PHYTOCIDAL AMOUNT OF A COMPOUND REPRESENTED BYTHE FORMULA:
 2. The method of claim 1 wherein R is selected from thegroup consisting of lower alkyl containing from 1 to 8 carbon atoms,lower alkenyl containing from 3 to 8 carbon atoms, and lower cycloalkylcontaining from 3 to 8 carbon atoms.
 3. The method of claim 1 wherein Ris lower alkyl containing from 1 to 8 carbon atoms.
 4. The method ofclaim 1 wherein the compound is represented by the structural formula:5. The method of claim 4 wherein the compound is2,3,6-trichloro-4-(methylthio)phenol.
 6. The method of claim 4 whereinthe compound is 2,3,5,6-tetrachloro-4-(methylthio)phenol.
 7. A method ofkilling weeds which comprises bringing inTo mutual contact the weeds anda phytocidal amount of a compound represented by the structural formula:8. The method of claim 7 wherein R is selected from the group consistingof lower alkyl containing from 1 to 8 carbon atoms, lower alkenylcontaining from 3 to 8 carbon atoms, and lower cycloalkyl containingfrom 3 to 8 carbon atoms.
 9. The method of claim 7 wherein R is loweralkyl containing from 1 to 8 carbon atoms.
 10. The method of claim 7wherein the compound is represented by the structural formula:
 11. Themethod of claim 10 wherein the compound is2,3,6-trichloro-4-(methylthio)phenol.
 12. The method of claim 10 whereinthe compound is 2,3,5,6-tetrachloro-4-(methylthio)phenol.
 13. A methodof precluding the establishment of a weed population in the soilcomprising applying to the soil an effective amount of a compoundrepresented by the structural formula:
 14. The method of claim 13wherein R is selected from the group consisting of lower alkylcontaining from 1 to 8 carbon atoms, lower alkenyl containing from 3 to8 carbon atoms, and lower cycloalkyl containing from 3 to 8 carbonatoms.
 15. The method of claim 13 wherein R is lower alkyl containingfrom 1 to 8 carbon atoms.
 16. The method of claim 13 wherein thecompound is represented by the structural formula:
 17. The method ofclaim 16 wherein the compound is 2,3,6-trichloro-4-(methylthio)phenol.18. The method of claim 16 wherein the compound is2,3,5,6-tetrachloro-4-(methylthio)phenol.